Various compositions are known to be useful as treating agents to provide surface effects to substrates. Surface effects include repellency to moisture, soil, and stains, and other effects, which are particularly useful for fibrous substrates and other substrates such as hard surfaces. Many such treating agents are fluorinated polymers or copolymers.
Most commercially available fluorinated polymers useful as treating agents for imparting repellency to substrates contain predominantly eight or more carbons in the perfluoroalkyl chain to provide the desired repellency properties. Honda et al, in Macromolecules, 2005, 38, 5699-5705 teach that for perfluoroalkyl chains of greater than 8 carbons, orientation of the Rf groups is maintained in a parallel configuration while for such chains having less than 6 carbons, reorientation occurs, which decreases surface properties such as contact angle. Thus shorter chain perfluoroalkyls have traditionally not been successful commercially.
Various attempts have been made to improve particular surface effects and to increase the fluorine efficiency; i.e., boost the efficiency or performance of treating agents so that lesser amounts of the expensive fluorinated polymer are required to achieve the same level of performance or have better performance using the same level of fluorine. It is desirable to reduce the chain length of the perfluoroalkyl groups thereby reducing the amount of fluorine present, while still achieving the same or superior surface effects. U.S. Pat. No. 3,576,018 discloses fluorinated acrylamide monomers useful as oil and water repellent agents containing a perfluoroalkyl or fluorinated isoalkoxyalkyl having 3 to 17 carbon atoms. No polymers or copolymers are disclosed.
There is a need for polymer compositions which significantly improve the repellency and stain resistance of fluorinated polymer treating agents for fibrous substrates and hard surface substrates while using lower levels of fluorine. The present invention provides such compositions.